1. Field of the Invention
This invention relates in general to gas pressure controllers and equipment, and more specifically to a two-stage hybrid gas pressure regulator suitable for use therein.
2. Description of the Related Art
Mechanical gas pressure regulators have been used for many years to reduce the pressure of a gas as the gas flows from a high-pressure fuel source to an end-use gas-consuming appliance. One gas-consuming appliance that is currently finding its way into portable electronic devices is the portable fuel cell. Fuel cells hold the promise of extending the operating time of portable electronic devices between charges, because of their high energy density—more than ten times that of conventional rechargeable batteries.
Unfortunately, fuel cells for portable applications can create some problems for conventional mechanical gas regulators. One problem is that such fuel cells require a precise, low gas pressure that must be maintained over a wide range of supply pressures. A second problem is that a fuel cell that is not under load can require near-zero gas flow, while the regulator still has to maintain the precise low pressure. Mechanical regulators do not lend themselves to great precision, particularly at near-zero gas flow. More recently, electronic regulators have been developed that can provide the precision and insensitivity to flow desirable for fuel cells. Electronic regulators, however, when used to reduce a typical high-pressure fuel source to the precise low pressure required for the fuel cell, require too much power for most portable electronic applications.